This study will investigate gene expression profiles in normal human lung tissue, lung carcinoma and metastatic tumor to the lung. The expression of up to 20,000 genes in a given lung tissue sample will be examined by cDNA microarray analysis and compared to normal lung tissue. In addition, we hope to identify a particular subset of lung cancer cells with an enhanced capacity for proliferation and self-renewal , analogous to the stem cells recently identified for certain types of leukemia, breast cancer and brain tumors.